Can You Choose How the Mortgage Payment Is Divided?
August 7, 2006, Reviewed July 11, 2007
"On my mortgage, I pay only part of the interest, with the unpaid
portion added to the balance. If I have extra cash, how should I apply
it, to the interest or to the principal."
You don’t have that option, in fact, no mortgage borrower does. The
allocation of a mortgage payment between interest and principal is
determined mechanically from the definitions of "interest" and
"principal".
Interest is the amount the lender is due for the period covered, usually
a month, and is calculated from the interest rate and the loan balance.
For example, if the loan is for $100,000 and the rate is 6%, the monthly
rate of .5% is multiplied by $100,000 to get $500 of interest due.
Principal is the payment minus the interest, and it is also equal to the
change in the loan balance. If the borrower pays $600, for example, then
$500 is interest and $100 is principal. The balance is reduced by $100,
which is called "amortization". If the borrower pays $400, the principal
is -$100 and the balance rises by $100, referred to as "negative
amortization".
In your case, the payment doesn’t cover the interest, let’s say it is
$300, which means that the principal payment is -$200. If you find
another $400 to add to the payment, it would raise the total payment to
$700, of which $500 would go to interest and $200 to principal. There is
no discretion involved. There never is.